function largestOfAll(arrs) {
  const maxValues = []
  for (const arr of arrs) {
    let maxValue = arr[0];
    for (const num of arr) {
      maxValue = maxValue > num? maxValue: num;
    }
    maxValues.push(maxValue);
  }

  return maxValues;
}

let output = largestOfAll([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]);
output = largestOfAll([[4, 9, 1, 3], [13, 35, 18, 26], [32, 35, 97, 39], [1000000, 1001, 857, 1]]);
console.log(output);